Apparatus for forming openings in furnace walls



Feb. 8, 1966 K. s. SVENDSEN 3,233,597

APPARATUS FOR FORMING OPENINGS IN FURNACE WALLS Filed Dec. 30, 1963 2SheetsSheet 1 V INVENTOR: Kommo 5. SVENDS'EN BY m HGENT Feb. 8, 1966 K.S. SVENDSEN APPARATUS FOR FORMING OPENINGS IN FURNACE WALLS Filed Dec.30, 1963 FIG. 5

2 Sheets-Sheet 2 INVENTOR:

KO/VRADi 5VEN05EN BY/%%@W APPARATUS FOR FORMING OPENINGS IN FURNACEWALLS Konrad S. Sven'dsen, Bloomfield, Conn., assignor to CombustionEngineering, Inc., Windsor, Conn, a corporation of Delaware Filed Dec.30, 1963, Ser. No. 334,522 4 Claims. (Cl. 122-235) This inventionrelates to openings in water cooled fur nace walls. More specifically,the invention is concerned with means and a method of forming an openingin a furnace wall lined with water cooled parallel tubes that areclosely spaced and welded to form a gas tight furnace enclosure.

In large water cooled furnaces such as those employed in connection withmodern steam generators a great number of openings are required in thefurnace walls. These furnace walls are lined on the inside or fire sidethereof with water carrying and parallelly arranged tubes. Severalinches of insulation is applied on the outside, which insulation isfurther enclosed by a metallic casing. In order to avoid hot spots orburning of the tube surface the flow of the cooling fluid (usuallywater) must be maintained continuously through the tubes even at theplaces where an opening in the wall is provided. Accordingly, the tubesmust be bent aside sufficiently to form a large enough opening betweenthe tubes for access by sootblowers, instrument inserts, observationports, etc.

Heretofore, this has been accomplished by bending a first tube away fromthe tube plane in a direction normal to this plane. Thus a space wasprovided for the &- setting of another adjacent tube which tube thencould be bent in the wall plane so as to occupy the space formerly takenup by the first tube. When bending tubes to form an access opening in atubular furnace wall, it is also desirable that the tubes which are bentaway from the wall plane remain within the normal space needed for theinsulation between the tube wall and the metallic casing. Accordingly,in order to provide an access opening two tubes wide by the aboveearlier method, four tubes had to be offset or a total of sixteen bendshad to be provided in the past to form one access opening. Since aconsiderable number of access openings (such as 100 to 150) must beprovided in the furnace wall of a large steam generator, this earlierpractice of forming an opening by bending four tubes proved to be veryexpensive. Furthermore, in using this construction it is also quitedifficult to seal the tubular structure surrounding the opening so as toobtain a gas tight construction.

These conditions have been greatly improved by the herein disclosedmethod and structure for forming access openings in water cooled tubularfurnace walls. In accordance with the invention this is accomplished byreducing thenumber of tubes that must be offset by half, and stillretain those tubes within the normal space pro vided between the casingand the tube lining for "insulation. Furthermore, the herein disclosedstructure permits less expensive and more effective gas tight sealing ofthe tubular structure forming the access opening.

It is accordingly an object of the invention to provide openings in thewater cooled tubular walls of a furnace chamber in a manner whichreduces the construction costs thereof considerably.

It is another object of the invention to provide a tubular structure forforming an opening in a tubular wall, which structure can be sealedagainst furnace pressure and radiant heat with greater efficiency andeffectiveness.

Other objects and advantages of the invention will become apparent fromthe following description of an il- United States Patent O 2,233,597Patented Feb. 8 1966 l'lLStIfltllVC embodiment thereof, when taken inconjunction with the accompanying drawings wherein:

FIG. 1 is a cross-section taken through a tubular furnace wall whereinone tube has been bent out of the Way to permit access to the furnacechamber.

FIG. 2 is an elevational view of the tube lining when taken at line 2-42of FIG. 1.

FIG. 3 is a cross-section through the tubular wall when taken at line3-3 of FIG. 1.

FIG. 4 is a cross-section through a tubular furnace wall wherein twotubes have been bent out of the way to permit access to the furnacechamber.

FIG. 5 is an elevational view of the tube lining when taken at line 55of FIG. 4. l

FIG. 6 is a cross-section through the tubular wall when taken at line6-45 of FIG. 4.

Referring now to the drawings wherein like reference characters are usedthroughout to designate like elements, the illustrative and preferredembodiment of the invention depicted therein includes a tubular wall 10of a furnace chamber. Wall 10 comprises a plurality of parallel tubes 12lining the fire side of the furnace wall. These tubes are closely spacedand are preferably Welded to each other along their length at 14, toform a gas tight enclosure for the combustion gases. Insulationpreferably in the form of insulating blocks of suitable thickness isapplied at the outside of the tube well such as at 16. The furnace wallthen completely enclosed by a metallic casing 18.

FIGS. 1, 2 and '3 disclose a structure defining a wall opening 19 ofrelatively small width such as one tube wide. To form this opening aportion ofa single tube 20 is bent away from the wall plane 22 such asby a double offset. This double offset comprises a first oifset 23bending the tube in a direction away from the wall plane 22 anda secondoffset 24 bending the tube 20 in a direction towards and back into thewall plane 22. The first and second offsets are executed in an offsetplane 25 which forms an acute angle 26 with the wall plane or tube plane22. In order to produce a double offset in such a manner that the bentportions thereof remain within the space provided for insulation 16 athird bend 28 is applied to the offset portion of tube 20. This thirdbend 28 imparts to the tube offset a curvature which follows the contouror periphery of an imaginary curved bod-y or body of rotation 30indicated by a dot and dash line. This curvature is so applied that theconcave side thereof faces the tube plane 22. The axis 32 of the curvedbody or body of rotation 30 is preferably maintained in parallelrelation with the wall plane 22 or with tubes "12. Suitable inserts 33and 34 are welded to the offset portion of tube 20 and to adjacent tube36 and to a conduit portion 37 which defines the access opening .19 forthe passing therethrough of a sootblower or instrument insert or thelike;

FIGS. 4, 5 and 6 disclose a structure defining a wall opening 39 ofapproximately twice the width than that illustrated in FIGS. 1, 2 and 3.To form this opening portions of two adjacent tubes 40 and 41 are bentin opposite directions and away from the wall plane 42 such as by adouble offset. This double offset comprises a first ofiset 43 bendingeach tube 40 and 4 1 in mutually diverging directions and away from thewall plane 42, and a second otfset 44 bending each tube 40 and 41 inmutually converging directions and towards and back into the wall plane42. Pairs of the first and second offsets are executed in two opposingplanes 45 and 46, respectively, which form acute angles 47 and 48,respectively, with the wall or tube plane 42. These acute angles are ofopposite configuration so that the apexes thereof face each other.

Again as in FIGS. 1, 2 and 3, in order that the bent portions of tubes40 and 41 remain within the space normally allotted to insulating blocks16, an additional bend 50 is applied to each of the opposite portions oftubes 40 and 41. Each of said bends 50 follows the periphery of animaginary curved body or body of rotation 52 and 54 as indicated in dotand dash lines. The respective axes 56 and 58 of these curved bodies orbodies of rotation are preferably maintained in parallel relation withthe wall plane 42 and with tubes L2, and are however located so as to beoutwardly spaced from opposite sides of said opening 39. Suitableinserts 60 and 62 are welded to the opposite portions of tubes 40 and4:1 and to adjacent tubes 64 and 66, and to conduit portion 68 whichdefines the access opening for the passing therethrough of sootblowerelements or insertion of observation doors and the like.

While I have illustrated and described a preferred embodiment of myinvention it is to be understood that such is merely illustrative andnot restrictive and that variations and modifications may be madetherein without departing from the spirit and scope of the invention. I

therefore do not wish to be limited to the precise details set forth butdesire to avail myself of such changes as fall within the purview of myinvention.

I claim:

.1. In a furnace wall the combination of a wall lining on the heatedside of said furnace Wall, comprising a plurality of heat absorbing andfluid cooled tubes parallelly disposed in one plane, said tubes beingmutually spaced a distance substantially less than the tube diameter,means for forming an access opening in said wall lining, said openinghaving a width that is at least equal to the distance between twoalternate tubes, said means comprising a double offset in one of saidplurality of tubes, said double offset having a first offset bendingsaid tube in a direction away from the heated side of said wall and awayfrom the center of said opening, and a second offset bending said tubein a direction toward and back into said plane, the depth of said offsetbeing at least sufficient to place the offset portion of said tubeoutside of said width when viewed in a direction normal to said oneplane, and a bend applied to said double offset, said bend following theperiphery of an imaginary body of rotation having an axis directedtransversely to the direction of said double offset, and with theconcave side of said bend facing said one plane.

2. In a refractory furnace wall the combination of a wall lining on theheated side of said furnace wall, cornprising a plurality of heatabsorbing and fluid cooled tubes paralle-lly disposed in one plane, saidtubes being mutually spaced a distance substantially less than the tubediameter and lined on the cool side thereof with casing means,

means for forming an access opening in said wall lining,

said means comprising a double offset in one of said plurality of tubes,said double offset generally lying in a plane forming an acute anglewith said one plane and extending in a direction away from said heatedside, and a bend applied to said double offset, said bend following theperiphery of an imaginary elongated curved body of rotation having alongitudinal axis directed transversely to 'the direction of said doubleoffset, said bend being of limited dimension such as to place the offsetportion of said tube entirely within the space customarily providedbetween said tubular lining and said casing means.

3. In a furnace wall the combination of a wall lining on the heated sideof said furnace wall, comprising a plurality of heat absorbing and fluidcooled tubes parallelly disposed generally in the plane of said wall,said tubes being mutually spaced a distance substantially less than thetube diameter, means for forming an access opening in said wall lining,said opening having a width that is at least equal to the distancebetween two tubes that adjoin a pair of mutually adjacent tubes, saidmeans comprising a first double offset in a portion of a first one ofsaid pair of mutually adjacent tubes and a second double offset in anadjacent portion of the second one of said pair of mutually adjacenttubes, each of said first and second double offsets having a firstoffset bending each first and second tube in mutually divergingdirections away from said plane and away from the heated side of saidwall, and a second off-set bending each said first and second tube inmutually converging directions toward and back into said plane, thedepth of said offsets being at least sufficient to place the offsetportions of said pair of tubes outside of said width when viewed in adirect-ion normal to said one plane, and a bend applied to each of saiddouble offsets in opposite directions, each of said bends following theperiphery of an imaginary elongated curved body having a longitudinalaxis directed transversely to the directions of said double offsets, theconcave sides of said bends facing said Wall lining.

4. In a refractory furnace wall the combination of a wall lining on theheated side of said furnace wall, comprising a plurality of heatabsorbing and fluid cooled tubes parallelly disposed generally in theplane of said wall, said tubes being mutually spaced a distancesubstantially less than the tube diameter and lined on the cool sidethereof with casing means, means for forming an access opening in saidwall lining, said means comprising a first double offset in a portion ofa first one of said tubes and a second double offset in an adjacentportion of a second adjacent one of said tubes, each of said first andsecond double offsets generally lying in mutually diverging planesforming acute angles with said wall plane and extending in a directionaway from said heated side, and a bend applied to each of said doubleoffsets in opposite directions, each of said bends folllotwing theperiphery of an imaginary elongated curved body having a longitudinalaxis directed transversely to the directions of said double offsets,said axes being outwardly spaced from opposite sides of said opening,said bends being of limited dimensions such as to place the offsetportions of said tubes entirely Within the space oustornarily providedbetween said tubular lining and said casing means.

References Cited by the Examiner UNITED STATES PATENTS 2,011,026 8/1935Bailey et a1. 122-235 2,025,066 12/1935 Millar 122-235 2,346,715 4/1944Woodward et al. 122-235 FREDERICK L. MATTESON, JR., Primary Examiner.

KENNETH W. SPRAGUE, Examiner.

1. IN A FURNACE WALL THE COMBINATION OF A WALL LINING ON THE HEATED SIDEOF SAID FURNACE WALL, COMPRISING A PLURALITY OF HEAT ABSORBING AND FLUIDCOOLED TUBES PARALLELLY DISPOSED IN ONE PLANE, SAID TUBES BEING MUTUALLYSPACED A DISTANCE SUBSTANTIALLY LESS THAN THE TUBE DIAMETER, MEANS FORFORMING A WIDTH THAT IS AT LEAST EQUAL TO THE SAID OPENING HAVING AWIDTH THAT IS AT LEAST EQUAL TO THE DISTANCE BETWEEN TWO ALTERNATETUBES, SAID MEANS COMPRISING A DOUBLE OFFSET IN ONE OF SAID PLURALITY OFTUBES, SAID DOUBLE OFFSET HAVING A FIRST OFFSET BENDING SAID TUBE IN ADIRECTION AWAY FROM THE HEATED SIDE OF SAID WALL AND AWAY FROM THECENTER OF SAID OPENING, AND A SECOND OFFSET BENDING SAID TUBE IN ADIRECTION TOWARD AND BACK INTO SAID PLANE, THE DEPTH OF SAID OFFSETBEING AT LEAST SUFFICIENT TO PLACE THE OFFSET PORTION OF SAID TUBEOUTSIDE OF SAID WIDTH WHEN VIEWED IN A DIRECTION NORMAL TO SAID ONEPLANE, AND A BEND APPLIED TO SAID DOUBLE OFFSET, SAID BEND FOLLOWING THEPERIPHERY OF AN IMAGINARY BODY OF ROTATION HAVING AN AXIS DIRECTEDTRANSVERSELY TO THE DIRECTION OF SAID DOUBLE OFFSET, AND WITH THECONCAVE SIDE OF SAID BEND FACING SAID ONE PLANE.